On Sunday at 3:05 p.m. EDT (12:05 p.m. PDT), an unmanned SpaceX Dragon capsule safely returned to Earth, splashing down into the Pacific Ocean 300 miles west of Baja California. The capsule, which undocked from the International Space Station earlier that day, returned over 3,500 pounds of NASA cargo and science samples.

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According to a NASA news release, included in the science payload is a medical studies investigation into the decreased effectiveness of antibiotics in space and the T-Cell Activation in Aging experiment, which is trying to understand how the human immune system responds to microgravity. Also included in the Dragon payload is an investigation into the cultivation of plants that may adapt to growing in a space environment.

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The Dragon capsule is currently the only cargo vehicle capable of returning experiments to Earth. The Orbital Sciences Cygnus capsule — the second private spaceflight company that (in addition to SpaceX) is being contracted by NASA to resupply the space station — burns up on reentry. The European Automated Transfer Vehicle, Russian Progress spacecraft and Japanese H-II Transfer Vehicle also do not have the capability of a soft landing, burning up on reentry.

The successful completion of this latest SpaceX resupply mission is the company’s fifth mission to the orbiting outpost and the third NASA-contracted Dragon resupply mission.